Graphical user interface for a display screen or portion thereof



FIG. 1 is a front view of a graphical user interface for a display screen or portion thereof; and,

FIG. 2 is a front view of a second embodiment thereof.

The broken line showing of a display screen in all views forms no part of the claimed design.

The AT&T trademark in the upper left corner of the Figures is a registered trademark of AT&T Intellectual Property II, L.P. Trademarks are the property of their respective owners. 

The ornamental design for a graphical user interface for a display screen or a portion thereof, as shown and described. 